unity8 is hung in SessionAuthorizer::requestAuthorizationForSession()

[Albert Astals Cid]

I was running
    phablet-test-run ubuntuuitoolkit
with the qt dbus patches that fix https://bugs.launchpad.net/ubuntu/+source/unity8/+bug/1421009

at some point the tests failed, i was left on screen with an application that is no longer running, and unity8 seems to be deadlocked

Using mir 0.12.0+15.04.20150228-0ubuntu1

[Gerry Boland (gerboland)]

Is using Mir 12.0: http://paste.ubuntu.com/10683940/

[Alberto Aguirre (albaguirre)]

Mir 0.12.1 addresses (to be released soon) some race conditions which can prevent a client Mir wait handle from signaling correctly (Thread 9 in the backtrace attached)

https://launchpad.net/mir/+milestone/0.12.1

[Daniel van Vugt (vanvugt)]

The server is blocked in QtMir (SessionAuthorizer) trying to authorize a new connection. I've seen this bug reported before. It is a duplicate. I just can't find the original bug report right now...

Thread 22 (Thread 0xae2ff450 (LWP 2300)):

#0 0xffffffff in __libc_do_syscall () at ../sysdeps/unix/sysv/linux/arm/libc-do-syscall.S:46
#1 0xffffffff in __pthread_cond_wait (cond=0xae358b20, mutex=0xae358b08) at pthread_cond_wait.c:186
#2 0xffffffff in QWaitCondition::wait(QMutex*, unsigned long) (time=4294967295, this=0xae358b08) at thread/qwaitcondition_unix.cpp:128
#3 0xffffffff in QWaitCondition::wait(QMutex*, unsigned long) (this=<optimized out>, mutex=mutex@entry=0xae35e160, time=time@entry=4294967295) at thread/qwaitcondition_unix.cpp:200
#4 0xffffffff in QSemaphore::acquire(int) (this=this@entry=0xae2feaf4, n=n@entry=1) at thread/qsemaphore.cpp:137
#5 0xffffffff in QMetaObject::activate(QObject*, int, int, void**) (sender=0xb1a3a064, signalOffset=<optimized out>, local_signal_index=<optimized out>, argv=0xae2feb38) at kernel/qobject.cpp:3685
#6 0xffffffff in SessionAuthorizer::requestAuthorizationForSession(unsigned long long const&, bool&) () at /usr/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqpa-mirserver.so
#7 0xffffffff in SessionAuthorizer::connection_is_allowed(mir::frontend::SessionCredentials const&) () at /usr/lib/arm-linux-gnueabihf/qt5/plugins/platforms/libqpa-mirserver.so
#8 0xffffffff in mir::frontend::ProtobufConnectionCreator::create_connection_for(std::shared_ptr<boost::asio::basic_stream_socket<boost::asio::local::stream_protocol, boost::asio::stream_socket_service<boost::asio::local::stream_protocol> > > const&, mir::frontend::ConnectionContext const&) (this=0xb1a47f8c, socket=std::shared_ptr (count 2, weak 0) 0xae36d1e4, connection_context=...) at /build/buildd/mir-0.12.0+15.04.20150228/src/server/frontend/protobuf_connection_creator.cpp:65

[Daniel van Vugt (vanvugt)]

Found the original report. It was bug 1421308.

[Albert Astals Cid (aacid)]

Has nothing to do with that one, or either that one was incorrectly duplicated to 1421009

Also it's interesting since updating to Mir 12.1 from silo 13 seems to makes it go away.

[Daniel van Vugt (vanvugt)]

That one was possibly incorrectly marked as a duplicate. Because this bug shows a hang in an identical location to that of bug 1421308:

Compare comment #6 above with:
https://bugs.launchpad.net/qtmir/+bug/1421308/comments/5

[Gerry Boland (gerboland)]

This hasn't happened in a while. It is usually due to the Qt GUI loop being blocked.